There is increasing evidence that processing and transport controls plan a major role in adenovirus 2 gene expression at early times after infection. The exact nature of the RNA's synthesized, their rates of synthesis, and the arrangement on the genome of the transcription units coding for these RNA's is not known at this time. The experiments outlined in this proposal are designed to characterize early viral gene expression with an emphasis on defining processes in viral RNA metabolism where regulatory controls may act effectively. The principal technique to be utilized is the exhaustive hybridization of pulse-labeled viral RNA to separated strands of Ad 2 DNA fragments. The experiments are designed to quantitate and characterize the RNA synthesized from various regions of the DNA. In some experiments UV-irradiation is used to alter gene expression. This alteration of Ad 2 genomes with increasing UV dosage is used to define the number and size of the transcription units. The experimental results can then be used to construct a map of the Ad 2 transcription units that are expressed at early times. By focusing on the differences in metabolism between those RNA's that become functional viral mRNA and those that are restricted to the nucleus, it become possible to define the points at which regulation may occur. It is important to clearly characterize viral RNA metabolism at early times since this information will facilitate our understanding the mechanism of cellular transformation. In this light, experiments utilizing UV-irradiated virus are outlined which may be able to increase our understanding of the function of early viral proteins and, possibly, help to identify the role they may play in viral transformation.